1. Field of the Invention
This invention relates generally to wheeled vehicles with a flexible power transmission mechanism such as a chain or belt. More particularly, this invention relates to devices for the adjustment of tension in a flexible power transmission mechanism.
2. Description of Related Art
Wheeled vehicles such as motorcycles generally have a drive sprocket or pulley attached to the drive shaft of the motor. The drive sprocket or pulley is then coupled to a flexible power transmission mechanism. In the case of the drive sprocket, the flexible power transmission mechanism is a chain.
Alternately, in the case of the drive pulley, the flexible power transmission mechanism is a belt. The chain or belt is then coupled to a sprocket or pulley affixed to driven wheel. The driven wheel is mounted to an axle that is secured to the frame of the motorcycle. Generally the frame of the motorcycle has a forked swing arm. The axle is secured to the swing arm. The swing arm allows vertical movement of the driven wheel. This vertical movement is dampened by a shock absorbing system connecting the swing arm and a rigid portion of the frame.
As is known in the art, the chain or belt must have correct tension to efficiently transfer power from the motor to the driven wheel. Motorcycles such as those manufactured by Yamaha Motor Corporation, USA, Kawasaki Motors Corp. U.S.A., American Suzuki Motor Corporation, Ducati Motor Holding S.p.A., and other motor cycle manufacturers integrate a chain tensioner or puller with the driven wheel of their motor cycles. The chain tensioner is coupled to the forks of the swing arm and is placed in a recessed axle slot of the forks. The chain tensioner is attached to the axle of the driven wheel.
In many of the current models of motorcycle, the chain tensioner is placed forward of the driven axle. The chain tensioner pushes the axle within an axle bore that is opened within the recessed guide of the forks. The chain tensioner is often adjusted by rotating a threaded stud captivated in a housing placed in the recess guide and secured to the forks. The threaded stud generally has a hexagonal head that is adjusted with a standard wrench. For motorcycles involved in “off-road” touring or racing, the chain tensioner often becomes fouled with mud and debris. This makes the adjustment difficult. Further, the size of the hexagonal head of the threaded stud is normally small and it is difficult to perform the adjustment during a race or in an “off-road” environment.
U.S. Pat. No. 6,450,282 (Gogo, et al.) describes a swing-arm support structure for a motorcycle. The swing-arm illustrated shows a slide adjuster mechanism for adjusting the tension of a chain of a motorcycle.
U.S. Pat. No. 5,524,725 (Schantzen) illustrates a chain drive that has an automatic chain tension adjustor.
U.S. Pat. No. 5,337,849 (Eavenson Sr., et al.) details a mechanism for mounting an axle to a vehicle. An adjustable tensioning mechanism includes a bolt and nut for shifting the second axle housing with respect to the first axle housing to thereby adjust the tension in the chain.
U.S. Pat. No. 5,049,114 (Hayden) describes a self-adjusting chain tensioning device made up of a spring loaded rubbing block that is in continuous contact with the chain.
U.S. Pat. No. 4,616,729 (Kasai) details a transmission chain adjuster for motorcycles. An arrangement is provided for adjusting the tension in each of two chains and one of these adjusting mechanisms moves the pivot point of the trailing arm relative to the frame.
U.S. Pat. No. 4,237,744 (Jolly) describes a chain tension adjusting device using a cam mounted within a sleeve that moves a driven wheel axle on a fork frame.
U.S. Pat. No. 4,061,050 (Bolger) illustrates a compensating mechanism to provide constant tension between a driving sprocket and a driven sprocket of a motorcycle.
U.S. Pat. No. 5,240,087 (Parker) describes a one-sided rear swing arm suspension system for a motorcycle with a chain-driven rear wheel. The tension of the drive chain may be adjusted without affecting the ride height of the motorcycle by an adjustment yoke that moves the axle longitudinally on the swing arm by means of an adjustment stud extending from the swing arm, and a corresponding adjustment nut entrapped in the neck of the yoke.
U.S. Pat. No. 5,964,312 (Maldonado) has a combination suspension swing arm and light assembly also serving to cover the axle nuts and axle adjustment screws for a motorcycle. The lenses are removable to expose both axle nuts and axle adjustment screws, permitting the full adjustment of both.